Disc brake having wear compensating mechanism

Abstract

A disc brake having a brake shoe wear compensating mechanism in which the sealing gaskets for the operating chamber formed between a pair of spreading members are arranged to be elastically deformable during a brake application, so as to exert a return force during a brake release. A joining element is provided between the spreading members, which utilizes a spring and the friction connection between the joining element and one of the spreading members to exert a return force independently of the return force exerted by the sealing gaskets, to thereby assure a sufficient brake release stroke.

Having now described the invention, what we claim as new and desire to secure by Letters Patent, is: 
     
       1. In a disc brake having at least one brake member and at least one disc member with which said brake member is engageable to effect a brake application, actuating apparatus comprising: (a) a pair of spreading members cooperatively arranged to form a chamber therebetween;   (b) a joining element between said pair of spreading members;   (c) a stop on one of said spreading members to limit the degree of axial movement of said joining element relative to said one of said spreading members;   (d) a first elastic ring between said joining member and the other spreading member to provide a fluid pressure seal and a friction coupling therebetween, said friction coupling effecting axial displacement of said joining element toward engagement with said stop, when fluid under pressure is supplied to said chamber to actuate said pair of spreading members and thereby force said at least one brake member into engagement with said at least one disc member;   (e) a second elastic ring between said joining element and said one spreading member to provide a fluid pressure seal for said chamber; and   (f) resilient means operatively disposed between said joining element and said one spreading member for exerting an axial force on said joining element in a direction away from said stop, so that upon the release of said fluid under pressure from said chamber, said joining element is shifted a predetermined distance away from said stop, whereby said friction coupling between said joining element and said other spreading member is effective to retract said other spreading member in a direction to effect disengagement between said at least one brake member and said at least one disc member and thereby release said brake application.   
     
     
       2. Actuating apparatus as recited in claim 1, further characterized in that said friction coupling is stronger than the force exerted by said resilient means on said joining element, whereby said first elastic ring is deformed when said spreading members are actuated to effect said brake application, the stress of said deformed elastic ring being such as to exert a return force on said spreading members in conjunction with the force exerted by said resilient means to release said brake application when fluid under pressure is released from said chamber. 
     
     
       3. Actuating apparatus as recited in claim 1, wherein said resilient means comprises a spring. 
     
     
       4. Actuating apparatus as recited in claim 1, wherein said second elastic seal ring includes said resilient means. 
     
     
       5. Actuator apparatus as recited in claim 4, wherein said second elastic seal ring is deformable and includes a spring comprising said resilient means embedded therein. 
     
     
       6. Actuator apparatus as recited in claim 4, wherein said second elastic seal ring comprises a solid block of elastomeric material. 
     
     
       7. Actuator apparatus as recited in claim 1, further comprising a third elastic ring between said one and said other of said spreading members to provide a friction connection therebetween and to further provide a seal for said chamber, said third elastic ring being deformable in response to said actuation of said spreading members during said brake application, whereby the tension of said deformation exerts a force on said spreading members in a brake release direction.